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w. J. DERICKSONQ Ten-Foot Extension-Rule.

No. 224,401. Patented Feb.10, 1880.

RARMYR, M5NINGTON. D. C

UNITED STATES PATENT OFFICE.

WILLIAM J. DERIGKSON, OF CLAYTON, CALIFORNIA, ASSIGNOR on one.

HALF OFY'HIVS RIGHT TO LABS P. OHRISTIANSEN, OF SAME PLACE.

TEN-FOOT EXT ENSlON-RULE.

' SPECIFICATION forming part of Letters. Patent No. 224,401, dated'February 10, 1880.

3 Application filed August 8,1879.

To all whom it may concern: 1

Be it known that I, WILLIAM J. DERIGKSON of Clayton, county of Contra Costa, and State of California, have invented an Improved Ten- Foot Extension-Rule; and I hereby declare, the following to be a full, clear, and exact de scription thereof.

My invention relatesto an improvementin carpenters measuring-rules, and refers more particularly to what are commonly known as ten-foot poles.

My improvements consist in forming the rule in four pieces, whichmay be joined together, and in certain details of construction by which the rule is adapted for both inside and outside measurement. Combined with this rule are removable trammel-points, by

means of which curves or circles may bede-V scribed of specified dimensions, asis more fully ing plate, a, in the guide a down on the part B, so the two parts may be held in any desired position with relation to each other. By having the sliding plate a under the set-screw the rule is not scratched in sliding through the guide, and the two parts may move by each other freely, while at the same time a larger Irictionalsurface is given when it is screwed down.

The extension pieces or parts 0 D fit into slots at in the ends of the parts A B, the'snaphook e in said extension engaging in slots f in the parts A B, and setting down flush when joined, as shown. s

At the ends of the parts AB are'the hinged plates or flaps g, and similar flaps g are placed at the ends of the parts 0 D. These plates are provided with springs on their spindles,

so they will bekept down flush when closed,

and may be raised by the thumb and used in. taking outside measurements, as hereinafter described.

On the outer ends of the parts 0 D are clamps h, having set-screws i and sliding plates 5 5 j, for securing said clamps on the rule. A small shoulder or projection, k, is formed on the clamp, in which is fixed a trammel-point, I, this point being placed on the shoulder 'so its point will be true with the end of therule 6o when the edge of the clamp is' flush with the end of the rule. These trammel-points are used for describing circles or arcs of any desiredsize within the scope of the rule, and by sliding the parts by each other the dimensions 6 5 separated to their widest points. The parts 0 D are then placed beside the other parts,

and'thewhole only'occupies a space equal in length to the longest part and about two inches I by two inches, and can be packed in an ordinary carpenters chest.

To use the rule where no more than five feet need be used. For ordinary measurements the two parts may he slid by each other in their guides until the proper place is reached,

when they can be fixed together by the setare to be measured, the two parts A B only 8 screw, the graduated scale showing the dimensions in inches and twelfths. In taking this measurement, after the parts are fixed together, by looking at the scale on the side A next to the guide. carrying the set-screw, the dimensions may be read off. For outside meas- 0 end of thething being measured is touched. 5

Theset-screw is fixed, and. by reading on the side A at the end of the offset m the dimensions are recorded. The ofl'set min the guide is formed there to allow for the position-of the flap 9 at the end of the part B,it being placed not quite at the end, as shown.

For measuring lengths longer than five feet the extensions 0 D are fitted to the parts A B, as described, so when all the parts are extended to full length a ten-foot rule will be formed. For inside measurement with the joined parts they are slid by each other until the two ends touch the ends of the inside of a box, for instance, and the set-screw is turned. Then, by looking on the side A at the end of the partA carrying the set-screw guide a, the dimensions are read off on the scale.

For outside measurements both of the flaps g are turned up and caught against an article being measured by sliding the parts by each other until the flaps catch. Then the, measurement is read off on the side A by looking at the index or ofiset m on the guide a, the edge of this index or offset marking the measurement when the flaps g are used.

To measure circles or arcs of circles the trammel-clamps are put in place on the ends, as described. The parts are adjusted by each other until the proper size is reached, when one point is placed down and the other describes the are or circle around it of the required size.

Pencil-points may be used instead of trammel-points, if desired. The trammels may be put on the ends of the short pieces A B, or may be slid up or down either of the parts to suit requirements.

The ordinary ten-foot poles used by carpenters, bricklayers, and other workmen are very troublesomefrom thcirinconvenientsize. New ones have to be made very frequently, and the fractions of feet have to be measured with the two-foot rules, they not being marked on the pole. Two rules have therefore to be used to get one measurement. Then, again, two pieces are lapped upon each other, nailed together, and then measured in taking inside measurements.

My deviceovercomes these obstacles by making the rule in the four parts, which slide by each other, as described, and whenever a measurement is taken either inside or outside the dimensions are markedon the scale accurately in feet, inches, and fractions, as shown.

The whole rule may, when closed, be placed in the chest with the ordinary tools.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The rule consisting of the parts A B, with the guide-clamps a a. and set-screw b, and having the slots or sockets d in the ends with the catch-slots f, in combination with the exterior pieces, 0 D, with their snap-hooks 6, whereby an extension ten-foot rule is formed which is capable of being adjusted and folded up when necessary, substantially as herein described.

2. In combination with an extension -rule formed in four parts, A B G D, adjustable with relation to each other, the flaps or plates 9 g, and the oflsets m m, for taking outside measurements, substantially as herein described.

3. In combination with an adjustable extension-rule for linear measurement, the clamps h, with their set-screws i, sliding platesj, and shoulders Ic, carrying the tramlnel-points l, whereby the points are in exact line with the end of the rule, and circles or arcs may be described, snbstantially as herein described.

In witness whereof I have hereunto set my hand.

\VILLIAM J. DERIOKSON. 

